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    Multicast ECID

    Traffic sent between aggregation devices and satellite devices is sent over a logical path, called an e-channel. The packets sent between the aggregation device and satellite device include the E-channel tag (ETAG) header with an E-channel identifier (ECID). The ECID identifies the path that will be used in forwarding traffic packets. Each extended port is identified by a unique ECID value. Junos Fusion reserves ECID values 1 through 4095 for unicast data packets and reserves ECID values from 4096 through 16382 for multicast and broadcast data packets.

    For unicast traffic and multicast traffic when local replication is disabled, the aggregation device assigns a unicast ECID value for each extended port. When local replication is enabled, Junos Fusion uses ECID values greater than 4095 to identify multicast traffic. Multicast ECID values can represent more than one port on a satellite device. The aggregation device creates a virtual interface to represent the satellite device (sd-<fpc-id>/0/0) and uses the virtual interface as the next-hop interface.

    The multicast ECID value assignments are dynamically assigned by satellite devices. When the aggregation device requires a new multicast ECID value for a group of ports or if it needs to add a port to an existing ECID, the process is as follows:

    1. The aggregation device sends a request to the satellite device for an ECID value that includes a reference ID.
    2. The satellite device assigns an ECID value and adds an entry to its ECID table to map the ECID value to the extended ports.
    3. The satellite device sends a message back to the aggregation device with the reference ID and the ECID value to use to represent the extended ports.
    4. The aggregation device adds the information to its ECID table. It uses the virtual interface as the next-hop interface to send multicast traffic for those extended ports on the satellite device.

    When the satellite device receives data packets with that ECID value, the satellite device can begin to replicate and forward packets to those extended ports.

    Note: The ECID value is only unique locally on the satellite device. Another satellite device can use the same ECID value for its own extended ports. The aggregation device maintains a mapping of ECID values for the different satellite and for the extended ports on the satellite device.

    Modified: 2016-10-19